In the 70's, 80's and early 90's I did a lot of deer smacking with a .257 WM near everything (other than a few Coyotes) was taken with a hand loaded 100 gr BT bullet of one type or another; loved it. Spend a lot of time on a Pre 64 Win 70 .270 great combo.. but I liked the .257 WM better. The 6.5 Creed, well I put a couple down range (friends rifles) on the 1k range.. super caliber, as for the cartridge, for what it does; it does it well.
I thought of a 6.5mm many times in the pasted, like some many back then, it was an "none American" and Elmer and Jack weren't talking much about them.
With today's bullets and powders'.., along with great rifle barrel makers'.., I think I'd be all over the .264 Win Mag.
Some time after the 6.5 Rem Mag was brought out... they ran some 6.5 Rem Mags in a M700 BDL I picked one up'..., why I didn't just by a .264 Win Mag; I'll never quite understand, but the rifle shot great, still the bullets weren't there yet so I used it as a back up to .257 WM for awhile then sold it to a friend in the early 70's.
Today that rifle and caliber (6.5 Rem Mag) would be a death ray, not as fast as the 6.5 Win Mag, but accuracy was over the top.
So to shorten this; I'd go with a 264 WM'..., you have the rifle and action for it.